The present invention relates to a solenoid for electromagnetic valve.
Conventionally, the following electromagnetic valve has been well known although not shown in particular. The electromagnetic valve includes a bobbin around which a coil is wound, a stationary iron core mounted to the center hole of the bobbin, a magnetic frame surrounding these iron cores, a movable iron core slidably inserted into the center hole of the bobbin, a solenoid part having a return spring, and a valve part. The valve part has a plurality of ports, a valve seat provided in a passage for communicating these ports, and a valve body, which is driven by the movable iron core so as to open and close the valve seat.
Further, it has been well known to connect a plurality of electromagnetic valves to a manifold base to a manifold base so that they are collectively controlled although not shown in particular.
When making manifold a plurality of electromagnetic valves, a problem arises such that the whole of electromagnetic valves is made into a large size, and becomes too heavy. For this reason, a body width of individual electromagnetic valves is made into a small size, and thereby, it is significant to miniaturize the whole of electromagnetic valve.
However, in this case, when the body width of the electromagnetic valve is made small in order to miniaturize the whole of electromagnetic valve, a winding outer diameter of solenoid driving a valve body of electromagnetic valve received in a body (housing) becomes small. Thus, when the winding outer diameter of solenoid becomes small, a problem newly raises such that an attraction force of solenoid is reduced, and further, a driving force for driving the valve body of electromagnetic valve is reduced.
Further, in order to increase an attraction force of solenoid, when the number of turns of coil is increased, and when the iron core is made to a large diameter, a problem arises such that the winding outer diameter of solenoid becomes large, and the cost increases.
Therefore, the conventional solenoid for electromagnetic valve has a limitation in its miniaturization and increase of attraction force.
In the present invention, the inventors have found that the above problems can be solved by making the following design. More specifically, in order to mount a manifold to a plurality of electromagnetic valves, even in the case where a body of individual electromagnetic valves is made small, the inventors have found that there is a margin in a body width and in a depth of electromagnetic valve in a right-angled direction. Then, they have devised each sectional shape of stationary iron core and movable iron core and a shape of center hole of bobbin in a solenoid of electromagnetic valve. Further, the inventors have confirmed that the above devise is suitably made within a range of the above margin, and thereafter, the present invention has been proposed.
Accordingly, an object of the present invention is to provide a solenoid for electromagnetic valve, which has a small size and large attraction force, and is excellent in economization.
In order to achieve the above object, the present invention provides a solenoid for electromagnetic valve comprising:
a bobbin around which a coil is wound;
a stationary iron core mounted into a center hole of the bobbin;
a movable iron core slidably inserted into the center hole of the bobbin, and having an attraction acting surface in the center hole of the bobbin so as to be attracted by current application to the coil; and
a magnetic frame surrounding the bobbin, the stationary iron core and the movable iron core,
the stationary iron core, the movable iron core and the center hole of the bobbin having an elliptic or substantially rectangular cross section,
a relation of d=(0.4 to 0.8) W being formed between a winding outer diameter W on a shorter axis or shorter side of a coil wound around the bobbin and having an elliptic or rectangular cross section and a diameter xe2x80x9cdxe2x80x9d of virtual cylindrical iron core having the same cross section as the coil inside cross section S,
a ratio of a length xe2x80x9caxe2x80x9d of a longer axis or side to a length xe2x80x9cbxe2x80x9d of a shorter axis or side being set to a range of 1.3xe2x89xa6a/bxe2x89xa63.0 in the cross section of the stationary iron core and the moving iron core.
According to the present invention, the solenoid for electromagnetic valve includes: the a bobbin around which a coil is wound; the stationary iron core mounted into a center hole of the bobbin; the movable iron core slidably inserted into the center hole of the bobbin, and having an attraction acting surface in the center hole of the bobbin so as to be attracted by current application to the coil; and the a magnetic frame surrounding the bobbin, the stationary iron core and the movable iron core. In the solenoid for electromagnetic valve having a body width shorter than a body depth, the iron core has a cross sectional area such that the relation between a winding outer diameter W of the coil wound around the bobbin and a diameter xe2x80x9cdxe2x80x9d of the virtual cylindrical iron core is d=(0.4 to 0.8) W. By doing so, the following matter has been confirmed by the calculation described later; more specifically, a design is made so that it is possible to make large an attraction force acting between the stationary iron core and the movable iron core of the solenoid for electromagnetic valve.
Further, the stationary iron core and the movable iron core having the calculated diameter d have the shape of ellipse or substantially rectangular cross section rather than circle, and thereby, even if the iron core cross section area is the same, it is possible to obtain a large attraction force. In addition, a ratio of a length xe2x80x9caxe2x80x9d of a longer axis or side to a length xe2x80x9cbxe2x80x9d of a shorter axis or side is set to a range of 1.3xe2x89xa6a/bxe2x89xa63.0 in the elliptic or rectangular cross section of the stationary iron core and the moving iron core. By doing so, it has been confirmed by the calculation described later that a large attraction force is obtained for an invested cost.
Therefore, according to the present invention, it is possible to provide a solenoid for electromagnetic valve, which has a small size and large attraction force, and is excellent in economization.